This grant seeks to investigate the mechanisms by which PMN interactions with epithelial cells during transmigration activate 2-catenin-dependent signaling pathways in lung epithelial cells and the importance of these pathways in epithelial repair. We will determine the signaling pathways that trigger epithelial 2-catenin activation including E-cadherin cleavage by PMN elastase. We will determine the mechanisms by which 2- catenin activation promotes repair of epithelial injury induced by PMN transmigration in vitro and in murine models of ALI using gene-targeted mice.